1. Field of the Invention
The present invention relates to a capacitor for a car AC generator, which comprises a capacitor element in the inside space of a generator case.
2. Description of the Prior Art
FIG. 9 is a sectional view of a car AC generator disclosed by Japanese Patent Publication No. 6-87646, FIG. 10 is a front view of a capacitor disclosed by Japanese Laid-open Patent Application No. 7-213034, and FIG. 11 is a sectional view cut on line E--E of FIG. 10. In FIG. 9, reference numeral 1 denotes a generator case whose inside space is formed by fastening an aluminum front bracket 2 to an aluminum rear bracket 3 by a through bolt 4 in such a manner that they face each other. Denoted by 5 is a cylindrical stator composed of a core and a coil and supported by the inner wall of the front bracket 2 and the inner wall of the rear bracket 3 in the inside space of the generator case 1, 6 a generator shaft which is installed in a center portion of the front bracket 2 and a center portion of the rear bracket 3 through a front bearing 7 and a rear bearing 8 so that it can turn, 9 a pulley which is fastened to the generator shaft 6 projecting forward from the front bracket 2 by a nut 10 so that it can turn together with the generator shaft 6, 11 a cylindrical rotor which consists of a pair of a magnetic pole and a field core and is fitted onto the generator shaft 6 in the inside of the stator 5 so that it can turn together with the generator shaft 6, 12 a front fan which is fixed to the front side of the magnetic pole of the rotor 11, 13 a rear fan which is fixed to the rear side of the magnetic pole of the rotor 11, 14 a plurality of slip rings which are spaced apart from one another in a direction parallel to the axial direction of the generator shaft 6 and are fixed to the generator shaft 6 between the rotor 11 and the rear bearing 8 by an unshown insulating member so that they can turn together with the generator shaft 6, 15 a first resin part made from a synthetic resin and installed in the rear bracket 3, 16 a cylindrical slinger portion made from a synthetic resin and provided at the center of the first resin part 15 to surround the slip rings 14, 17 a brush holder portion made from a synthetic resin and provided in the first resin part 15 outside the slinger portion 16, 18 a plurality of brushes corresponding to the number of slip rings 14, which are inserted into the brush holder portion 17 and whose end portions projecting into the inside of the slinger portion 16 from the brush holder portion 17 are each contacted to the slip rings 14, 19 a plurality of brush springs for pressing the plurality of brushes 18 against the slip rings 14 elastically, and 20 a voltage control function portion made from a synthetic resin and provided in the first resin part 15 at the rear of the brush holder 17, to which a voltage regulator 21 is attached. Numeral 22 denotes a second resin part made from a synthetic resin and installed in the rear bracket 3 in such a manner that it does not interfere the first resin part 15, and 23 a rectifying function portion made from a synthetic resin and provided in the second resin part 22, to which a rectifier 24 comprising unidirectional conductive elements such as a diode is attached.
A description is subsequently given of the operation of the above car AC generator of the prior art when it is mounted on an automobile. The car AC generator is installed outside the cylinder block of an engine and a ring-shaped belt is stretched between a pulley provided on the crank shaft of the engine and the pulley 9 of the car AC generator. When a driver turns on the ignition switch of the automobile in this state, a current runs from the battery of the automobile to an ignition coil to start the engine and an excitation current runs into the brushes 18, the slip rings 14 and the field coil of the rotor 11 from the battery through the voltage regulator 21. When the generator shaft 6 turns by the start of the engine and then the rotor 11 turns in this state, three-phase AC induction electromotive force is generated in the coil of the stator 5, rectified by the rectifier 24 and charged into the battery. The front fan 12 and the rear fan 13 turn by the rotation of the rotor 11 so that air in the engine room of the automobile is sucked into the inside space of the generator case 1 through suction holes in the front bracket 2 and suction holes in the rear bracket 3. The intake air cools such parts as the stator 5, the rotor 11, the voltage regulator 21 and the rectifier 21 in the inside space of the generator case 1 and is then discharged into the engine room from exhaust holes in the front bracket 2 and exhaust holes in the rear bracket 3.
In FIG. 10, the first resin part 15 of the capacitor has a capacitor mounting portion 25 made from a synthetic resin on one side of the slinger portion 16 in addition to the slinger portion 16, the brush holder portion 17 and the voltage control function portion 20. The capacitor mounting portion 25 has a hole 27 extending through a plate-like base portion 26 projecting sideways from the slinger portion 16 and the brush holder portion 17 and two resin side terminals 28 provided in the base portion 26 around the hole 27 in such a manner that they face each other. A capacitor container 29 is installed in the capacitor mounting portion 25. As shown in FIG. 11, the capacitor container 29 contains a capacitor element 30 which is supported in the capacitor container 29 by a filling resin 31 such as an epoxy resin which is injected into a gap between the capacitor container 29 and the capacitor element 30 and solidified. The capacitor container 29 is inserted into the hole 27, and two element side terminals 32 projecting outward from the capacitor container 29 are connected to the respective resin side terminal 28 by solder 33. Therefore, the direction of injecting the filling resin 31 into the capacitor container 29 and the direction of connecting the element side terminals 32 to the respective resin side terminals 28 by the solder 33 are the same on the front side of the first resin part 15, thereby improving assembly work efficiency. The capacitor element 30 is interposed between the positive pole and the negative pole of the generator so that it is connected to these electrodes in parallel and absorbs a surge generated by the voltage control of the voltage regulator 21, thereby preventing the propagation of noise to car electric load devices such as an audio device and a blower fan.
Since the capacitor for a car AC generator of the prior art is constituted as described above, the capacitor container 29 separate from the first resin part 15 is inserted into the hole 27 of the first resin part 15 while the capacitor element 30 is fixed in the capacitor container 29 by the filling resin 31, and the connection portions of the resin side terminals 28 and the element side terminals 32 bear the weight of the capacitor container 29, the weight of the capacitor element 30 and the weight of the filling resin 31. When the car AC generator is connected to the engine of the automobile, the engine of the automobile is driven, and vibration is transmitted from the engine to the car AC generator, the weight of the capacitor container 29, the weight of the capacitor element 30 and the weight of the filling resin 31 serve as a vibration load on the connection portions of the resin side terminals 28 and the element side terminals 32 by the vibration repeatedly. Therefore, there is a possibility that these terminals are separated from each other. To cope with this, after the resin side terminals 28 are connected to the respective element side terminals 32 by the solder 33, end portions of the resin side terminals 28 projecting from the element side terminals 32 are bent inward so that bent portions 32 prevent separation between the resin side terminals 28 and the element side terminals 32. However, this requires the formation of the bent portions 34 and makes the structure complex.